Historically pre-treatment or anti-icing has been accomplished with the use of liquid products such as CaCl, MgCl, or brine. Recently, a transition has been made to higher pre-wet rates for solid applications because many crews seem to believe that this is a more cost effective method than liquid.
Clear Roads members were interested in learning about state DOT’s experiences with using prewetted solids or slurries for roadway anti-icing as an alternative to traditional liquid anti-icing. Specifically, they wanted answers to the following questions.
- What is the prevalence of this technique and what are the conditions when this approach may be appropriate?
- What is the cost/benefit of this approach when compared to traditional liquid applications?
- Is there an increased environmental impact to this approach? ie. more chloride on the road or more importantly off the road?
Through a literature search and survey of Clear Roads states, this project produced a synthesis report which summarizes state DOT practices related to prewetting of solid materials for anti-icing, including a description of which materials are used, what prewet rates and/or slurry rates are used, the most appropriate weather and road conditions for this technique, effects on the environment, regulatory issues, and success stories, challenges, and lessons learned.